Scientific Understanding of Consciousness
Consciousness as an Emergent Property of Thalamocortical Activity

Frontal Lobes

Frontal lobes are a large brain region representing 30% of the cortical surface. (Miller; Human Frontal Lobes, 9)

Cerebral cortex can be partitioned in two ways: (1) structurally or (2) functionally. (Miller; Human Frontal Lobes, 59)

Frontal lobes have three major divisions: motor, premotor, and prefrontal regions. (Miller; Human Frontal Lobes, 7)

Motor and premotor areas are considered distinctive functional units, whereas prefrontal cortex is more complex, requiring further subdivision. (Miller; Human Frontal Lobes, 7)

The frontal lobe contains multiple motor areas involved in the generation and control of limb movement. (Houk, et.al.; Models of Information Processing in the Basal Ganglia; Strick, et.al; Basal Ganglia Circuits, 117)

Left and right frontal lobes are differentiated. Left frontal lobe is more specialized for language-related functions. Right frontal region is dominant in social cognition and emotions. (Miller; Human Frontal Lobes, 7)

Lateral and medial views of the left cerebral hemisphere of the human brain (diagram) prefrontal, premotor, motor, central sulcus, lateral sulcus; paralimbic. (Miller; Human Frontal Lobes, 45)

Cortex -- especially the frontal lobes -- commands action and reaction and integrates our attention with short- and long-term goals. (Ratey; User's Guide to Brain, 115)

Prefrontal Cortex

Prefrontal cortex is parcellated into orbitofrontal, dorsolateral prefrontal, and medial frontal/anterior cingulate regions. (Miller; Human Frontal Lobes, 13)

Dorsolateral Prefrontal Cortex (DLPFC)

Orbitofrontal and dorsolateral components of the frontal lobes are distinctive. (Miller; Human Frontal Lobes, 9)

Dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortex (ACC). (Miller; Human Frontal Lobes, 44)

Anterior Cingulate Cortex (ACC)

Anterior cingulate cortex (ACC) lies on the medial surface of the cingulate gyrus, wrapping around the anterior portion of the corpus callosum. (Miller; Human Frontal Lobes, 49)

Orbitofrontal cortex (OFC)

Orbitofrontal cortex (OFC) and the insular; two major components of the paralimbic belt. (Miller; Human Frontal Lobes, 59)

Orbital and mediolateral portions of the prefrontal lobe are functionally correlated with emotional alterations and disinhibition of behavior. (Edelman; Remembered Present, 160)

Orbitofrontal patients may show by their behavior a blatant disregard for even the most elementary ethical principles. (Fuster; Prefrontal Cortex, 199)

Orbitofrontal cortex has a key role in representing primary reinforcers, and learning and rapidly changing associations between stimuli and primary reinforcers, and thus is important in many types of emotional and motivational behavior. (Rolls; Memory, Attention, and Decision-Making, 183)

Flavor representation -- convergence of taste and olfactory inputs in the orbitofrontal cortex. (Rolls; Memory, Attention, and Decision-Making, 151)

The orbitofrontal cortex is involved in the affective, reward-related, representation of touch. (Rolls & Treves; Neural Networks, , 154)

Orbitofrontal cortex is the cortex of the ventral aspect of the frontal lobe. It comprises mainly Brodmann areas 11 and 13. (Fuster; Prefrontal Cortex, 198)

Orbitofrontal cortex has important medial-lateral and right-left divisions. (Miller; Human Frontal Lobes, 7)

Inputs to the orbitofrontal cortex include many of those required to determine whether a visual or auditory stimulus is associated with a primary reinforcer such as taste or smell. (Rolls & Treves; Neural Networks, 153)

Orbital cortex is intimately and reciprocally connected with the limbic structures, especially the amygdala, the hypothalamus, and the monoaminergic systems of the brainstem. (Fuster; Prefrontal Cortex, 345)

Orbitofrontal networks collect diverse visceral inputs, as well as inputs conveying information related to basic drives, general states of the organism, and the motivational significance of sensory stimuli. (Fuster; Prefrontal Cortex, 345)

It is mainly in orbitofrontal cortex that information about actual and expected rewards is collected -- through the dopaminergic system -- and funneled to the rest of the prefrontal cortex to drive and shape behavior. (Fuster; Prefrontal Cortex, 345)

Orbital action domain is critically involved in emotion in two major ways -- (1) by acting on the cognitive networks of the cortical convexity to promote reward seeking behavior, and (2) by acting upon subcortical structures (the nucleus accumbens, hypothalamus, striatatum, etc.) and the autonomic and endocrine systems to support and control the major drives of the organism. (Fuster; Prefrontal Cortex, 345)

Signals of the basic drive and motivations of the organism arrive in prefrontal cortex via the orbitofrontal cortex, the diencephalon, and limbic formations. (Fuster; Prefrontal Cortex, 345)

Research study — Orbitofrontal Cortex Functions — orbitofrontal cortex is involved in decoding and representing some primary reinforcers such as taste and touch; in learning and reversing associations of visual and other stimuli to these primary reinforcers; and in controlling and correcting reward-related and punishment-related behavior, and thus in emotion.

Research study — Orbitofrontal Learning Using Inferred Values — orbitofrontal cortex is fundamental for accessing model-based representations of the environment when value is computed or inferred on the fly when it is needed.

Frontal Lobe Connections

Intimate connections between subcortical and frontal structures. (Miller; Human Frontal Lobes, 7)

The orbitofrontal cortex is strongly connected to the amygdala. (Rolls & Treves; Neural Networks, 151)

Prefrontal regions are reciprocally connected with temporal, parietal, and occipital cortices, where they receive higher-level visual, auditory, and somatosensory information. (Miller; Human Frontal Lobes, 49)

Diverse functional affiliations of the ACC reflect its widespread connections to the DLPFC. (Miller; Human Frontal Lobes, 49)

Medial orbitofrontal cortex is strongly connected with the hypothalamic nuclei. (Miller; Human Frontal Lobes, 7)

Lateral orbital cortex is strongly connected with the anterior temporal and insular regions. (Miller; Human Frontal Lobes, 7)

Connectivity of the frontal-subcortical circuits (diagram). (Miller; Human Frontal Lobes, 28)

It is estimated that 2-3% of all cortical neurons send projections to the contralateral hemisphere, most of which cross in the corpus callosum. (Miller; Human Frontal Lobes, 51)

Higher-order association areas tend to have the greatest density of commissural projections, whereas fewer interhemispheric connections are present between primary sensory and motor cortices. (Miller; Human Frontal Lobes, 51)

General pattern of callosal collectivity between prefrontal regions broadly reflects cortical topography along the anterior-posterior hemisphere axis. (Miller; Human Frontal Lobes, 51)

Corticocortical connections exhibit a modular functional architecture responsible for channeling patterns of activation in multifocal intra- and interhemispheric networks. (Miller; Human Frontal Lobes, 52)

Prefrontal regions have strong connections with limbic structures such as the hippocampus and amygdala, which mediate processes such as learning and memory, emotional and affective tone, autonomic regulation, drive, and motivation. (Miller; Human Frontal Lobes, 49)

Perception-Action Cycle uses Reentry and Recursion

Joaquin Fuster’s Perception-Action Cycle uses reentry and recursion on all hierarchical layers between the frontal motor cortical areas and the posterior sensory cortical areas.

Brain Functions as a Reality Emulator

The brain functions as a reality emulator to assist the animal with prediction and decisions to enhance survival. In this process the brain performs near-optimal Bayesian inference to continuously update its dynamic neuronal network model of reality with the stream of input data from the senses.

Brain operates as a reality emulator. (Llinás; I of the Vortex, 13)

Frontal Lobe Functionality

Five distinctive frontal subcortical systems

Five distinctive frontal subcortical systems: (1) supplementary motor area, (2) frontal eye fields, (3) dorsolateral prefrontal, (4) orbitofrontal, (5) anterior cingulate cortex. (Miller; Human Frontal Lobes, 7)

Working memory is a core constituent of executive function. (Miller; Human Frontal Lobes, 7)

Linguistic functions of Broca's area in prefrontal cortex. (Miller; Human Frontal Lobes, 7)

Right prefrontal cortex for social and emotional behavior. (Miller; Human Frontal Lobes, 7)

Right supplementary motor area. (Miller; Human Frontal Lobes, 7)

Movement disorders are particularly prominent when the basal ganglia component of frontal--subcortical circuits is affected. (Miller; Human Frontal Lobes, 8)

Cingulate cortex is particularly important for initiation of behavior. (Miller; Human Frontal Lobes, 9)

Broca's aphasia. (Miller; Human Frontal Lobes, 13)

Frontal-cortical regions are connected to a complex circuitry of subcortical structures. (Miller; Human Frontal Lobes, 14)

Modulating input from serotoninergic and dopaminergic nuclei. (Miller; Human Frontal Lobes, 14)

Medial frontal cortex comprises the supplementary motor area and the anterior cingulate cortex. (Miller; Human Frontal Lobes, 15)

Socially Acceptable Behavior

Right-hemispheric orbitofrontal regions mediate the rules of social convention. (Miller; Human Frontal Lobes, 15)

The two OFCs (medial and lateral) mediate empathetic, civil, and socially appropriate behavior. (Miller; Human Frontal Lobes, 30)

Orbitofrontal dysfunction causes social defects. (Miller; Human Frontal Lobes, 8)

Inferior frontal regions are known from lesion studies to be involved in social awareness and the ability to possess a value system and experience guilt; lesions in this region tend to produce uncensored and potentially antisocial behavior. (Andreasen, Creating Brain, 74)

Perhaps the connectivity between the medial inferior frontal region and the precuneus represents the network through which personal identity and past personal experiences are interlinked, with the net interactions permitting us to move between self-awareness and disengagement, censorship and freedom, or consciousness and the unconscious. (Andreasen, Creating Brain, 74)

Akinetic mutism occurs with bilateral lesions of the anterior cingulate cortex. (Miller; Human Frontal Lobes, 29)

Frontal lobe evolved to manage the pyramidal pathway. (Miller; Human Frontal Lobes, 38)

Anterior Cingulate Cortex an Integrating Center

Functional organization of the ACC reflects its central role as an integrated center for the cognitive-behavioral and emotional-autonomic-motor neural networks. (Miller; Human Frontal Lobes, 49)

Prefrontal association and paralimbic cortices play a major role integrating information about external world and internal states that guides executive behavior. (Miller; Human Frontal Lobes, 49)

Five Subtypes of Cortex

Functionally, five subtypes of cortex have been proposed: (1) primary sensory-motor; (2) unimodal association; (3) heteromodal association; (4) paralimbic; (5) limbic. (Miller; Human Frontal Lobes, 59)

Olfaction

Temporal-insular-orbitofrontal region is largely devoted to olfaction. (Miller; Human Frontal Lobes, 59)

Return to — Modularity of Brain

Link to — Consciousness Subject Outline